main {
    display: flex;
    flex: 1;
    overflow: scroll;
    /* 超出显示滚动条 */
    background-color: aquamarine;
    flex-direction: column;

    h1 {
        margin: 15px 0px;
    }

    .top {
        ul {
            width: 100%;
            display: flex;
            justify-content: space-around;
        }

        /* 顶部导航平均分开 */
    }

    .latest {/* 最新课程 */
        height: 170px;
        border: 1px solid red;
        border-radius: 20px;
    }

    .course {/* 下面课程 */
        border-radius: 20px;

        ul {
            display: flex;
            flex-direction: column;

            li {
                height: 120px;
                margin: 15px 0px;
                border: 1px solid red;
                border-radius: 20px;
                background-color: #e8e8e8;

            }
        }

    }

}